1. Field of the Invention
The present invention relates to a paper sheet feeding device for feeding a plurality of accumulated paper sheets one by one.
2. Description of the Related Art
A paper sheet feeding device is known by, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-326713. The paper sheet feeding device disclosed in this publication is incorporated in a mail processing apparatus for reading the addresses of mail items to sort them, and is designed to feed the mail items to a conveyance path one by one.
To this end, the feeding device comprises a receiving section (hopper) for simultaneously receiving a plurality of mail items upright; a supply mechanism for forwardly moving the received mail items and supplying them one after another toward a pickup position; a pickup belt designed to run along the pickup position for picking up each mail item by a suction force and transferring it to the conveyance path; a conveyance mechanism for pulling, using a nip, each mail item picked from the pickup position by the pickup belt and transferring it, at a speed slightly higher than the pickup speed; and a separation mechanism for separating mail items from the earliest picked one of the mail items when these mail items are picked up unintentionally simultaneously.
The feeding device also comprises a suction mechanism for applying air of negative pressure to the mail item (to be picked up earliest) positioned at the pickup position, thereby quickly positioning the same at the pickup position. The suction mechanism is located upstream of the pickup belt with respect to the pickup direction of mail items. By thus locating the suction mechanism adjacent to the pickup belt, a mail item to be subsequently picked up can be quickly positioned at the pickup position, whereby the pickup speed of mail items can be enhanced.
However, when mail items, such as relatively thin and short post cards, are fed by the above-described feeding device, so-called “simultaneous pickup,” in which a leading mail item and a subsequent one are simultaneously picked up, may well occur. Namely, immediately after a mail item, which is relatively short in the pickup direction, is moved to the pickup position by the suction force of the suction mechanism and then picked up therefrom by the pickup belt also using a suction force, the rear end of the mail item with respect to the pickup direction falls out of the range of the suction mechanism, and air of negative pressure is applied to the subsequent mail item by the suction mechanism.
At this moment, the rear end of the first-fed mail item is pressed against the pickup belt by the subsequent mail item, whereby these mail items tightly contact each other, the conveyance force of the pickup belt is also exerted on the subsequent mail item. This being so, such relatively thin and short mail items may easily be picked up simultaneously.